It takes place when magma introduces great amount of heat into an existing rock
resulting in the recrystallization and mineral
reaction in the rock.

The correct answer is - contact metamorphism.

Explanation:

Contact metamorphism is one of the two metamorphism processes which takes place when the pre-existing rock is introduced to a great amount of heat which affects it by an intrusion of magma. It is known as a low pressurized, high-temperature type of metamorphism.

An example of this type of metamorphism which experiences recrystallization in the rock and forms a metamorphic marble that is formed by the recrystallization and mineral reaction of the limestone.

but there is no

i guess you forgot putting it.

the law of original horizontality explains:   why rocks appear in layers. correct answer: b the law suggests that all rock layers are originally laid down (deposited) horizontally and can later be deformed.   the principle is used by geologists to make assumptions about the relative ages of sedimentary rocks.